When an edentulous patient is being considered for a full-arch implant-supported restoration, the conversation often centres on the number of implants and the choice of restorative material. But what happens several years after the prosthesis is delivered?
A new umbrella review has brought together long-term evidence on implant-supported complete-arch prostheses to examine not only how long these restorations survive, but also which complications tend to occur with different prosthetic designs and materials.
The review included systematic reviews reporting at least five years of follow-up for screw- or cement-retained implant-supported fixed complete-arch prostheses fabricated using metal-ceramic, metal-resin, veneered zirconia or monolithic zirconia.
Seven systematic reviews met the inclusion criteria.
Overall, the long-term survival figures were reassuring.
Prosthetic survival ranged from 89.5% to 96.8% over follow-up periods of five to 15 years. Implant survival was even higher, ranging from 95.2% to 99.2%.
In other words, the implants themselves continued to perform well over the long term, but technical complications involving the prosthesis remained an important part of maintenance.
The prosthesis may be where the problems begin
Among the complications reported across the included reviews, screw loosening occurred in approximately 5% to 15% of cases. Veneer chipping was reported in 15% to 35% of veneered zirconia restorations, while framework fractures were less common, occurring in fewer than 5% of cases.
The restorative material appeared to influence the type and frequency of complications.
Veneered zirconia demonstrated significantly higher rates of chipping compared with monolithic zirconia. This difference suggests that eliminating the veneering layer may reduce one potential source of technical failure.
Metal-ceramic frameworks, meanwhile, showed performance comparable with that of the other established restorative approaches in the analysis, with no significant difference reported in the comparison cited by the review.
The findings therefore point towards an important distinction: a high implant survival rate does not necessarily mean that the patient will remain completely free from prosthetic complications.
Four implants or six?
Another question frequently encountered in full-arch rehabilitation is whether increasing the number of implants from four to six provides better long-term survival.
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